1. Field of the Invention
The invention is directed to an articulated fitting for seats with adjustable backrest, in particular motor vehicle seats, in which a stationary articulated part associated with the seat part and a swivelable articulated part associated with the backrest are connected with one another via an adjusting shaft, with an adjusting and locking device which is constructed as a gear unit and determines the position of the two articulated parts relative to one another, the adjusting shaft having an eccentric portion for supporting one articulated part, this eccentric portion being formed by two wedge segments which are inclined relative to one another and engage regions of a driver of the adjusting shaft, by a driver arm engaging between the narrow sides of the wedge segments, and by a torsion spring which spreads apart the broad sides of the wedge segments with its spring legs.
2. Description of the Related Art
In a known articulated fitting of the type mentioned above, the driver has a sleeve, one end of which is connected so as to form one piece with a plate or disk projecting beyond the outer diameter of the sleeve. A driver arm which is spaced radially from the sleeve and engages over certain portions thereof is formed integral with this disk and engages between the narrow sides of two wedge segments whose outer surfaces support a bearing bore hole of one articulated part comprising a spur gear, for instance, while the inner surface area of the wedge segments is supported on a collar of the other articulated part, which collar supports the sleeve of the driver. Owing to operating and manufacturing tolerances, the two wedge segments are spread apart to varying degrees by the spring legs of a torsion spring which act upon the broad sides of the wedge segments so that the radian measurement of the space accommodating the driver arm, which is constructed as an annular segment and provided for acting upon the narrow sides of the wedge segments, is more or less extensive. When the radian measurement between the narrow sides of the wedge segments is small, the play existing between the stop faces of the driver arm and the narrow sides of the wedge segments is consequently smaller than it would if the radian measurement between the narrow sides of the wedge segments were greater due to occurring tolerances. Therefore, when the adjusting movement is initiated in the driver, the user must overcome a more or less considerable idle path before the driver arm acts upon one of the narrow sides of a wedge segment. This occurs with every change in the rotating direction of an adjusting movement manually initiated in the driver. This idle path effect is perceived by the user as irritating. Further, rattling noises occur when the vehicle is operated. Moreover, precision adjustment is difficult.